Many substance dependent individuals continue to abuse a variety of substances during treatment for their disorder. Often, substance dependent individuals are co-diagnosed with depression and violence problems. Supplements of n-3 polyunsaturated fatty acids (PUFAs) may play a role in treating individuals with such substance abuse problems. The purpose of this study is to evaluate the effectiveness of the n-3 PUFAs eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA) in treating relapse, aggression, and depression in substance dependent individuals.